A thin film transistor liquid crystal display device (TFT-LCD) is irradiated with light from a back side. In particular, light from a light source travels in an upward direction. A specific light pipe is arranged at a back side of liquid crystal, light from the light source irradiates the light pipe and then transmitted upward through a lower polarizer sheet. Since the upper and lower electrodes are a transparent electrode and a common electrode. When the transparent electrode is conducted, the appearance of liquid crystal molecules will change to block and transmit light for realizing the display function. The responsive time is improved up to about 80 ms. This kind of display device has a high contrast and rich color, and the screen has a fast refresh rate. Thus, a TFT-LCD display panel has become a mainstream product in the display field.
In a process for fabricating a TFT-LCD display panel, since the resolution of the display panel is increasingly higher, the number of signal lines which are connected with each pixel unit increases accordingly. This causes the signal lines cannot be arranged in a single layer of the fanout area. Thus, the signal lines have to be arranged alternately in different layers. As shown in FIG. 1, a display panel comprises a plurality of pixel units 10 which are arranged in an array, and each column of pixel units 10 is connected with a same one of the data lines 11. When the number of pixel units comprised in the display panel increases, the number of data lines increases accordingly. Thus, in the fanout area A of the display panel, the data lines are arranged more densely at corners, so that grooves 12 occur in the fanout area. Thus, during the subsequent layer processes, a coating machine generally operates in a spinning mode, so that difference in a photoresist layer may appear in the corner direction. This influences difference in size of a transparent conductive layer (ITO FICD) and difference in size of a source/drain layer (SD FICD). As a result, once the array substrate fabricated by this process is assembled with a color film substrate to form a display panel, the display panel suffers from skew defect (Mura).
With the display panel develops toward full high definition (FHD), data lines are arranged in the fanout area in a denser manner. In case data lines are arranged alternately in different layers, the grooves become serious, and accordingly the skew defect becomes serious.